High-voltage igniter system for electronic flashlights



June 27, 1967 s. THEIMERY 3,328,634

HIGH-VOLTAGE IGNITER SYSTEM FOR ELECTRONIC FLASHLIGHTS Filed April 15,1965 PISA,

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United States Patent 3,328,634 HIGH-VOLTAGE IGNITER SYSTEM FORELECTRONIC FLASHLIGHTS Siegfried Theimer, Hofstrasse 1, Offenbach amMain-Rumpenheim, Germany Filed Apr. 15, 1965, Ser. No. 448,461 4 Claims.(Cl. 315166) ABSTRACT OF THE DISCLOSURE This application discloses ahigh-voltage ignition system for electronic flashlights, such as xenonflashlights, which system is energized from an A-C current supply andwherein ignition is effected by an impulse circuit.

This invention has reference to high-voltage ignition systems forelectronic flashlights, and more particularly to ignition systems forigniting the flashlights, or flash lamps, of photographic copyingmachines, of photographic reproduction systems and of photographicenlargers.

This invention is more particularly concerned with high-voltage ignitionsystems for xenon lamps which are particularly desirable for the aboveapplications on account of their high efliciency, and on account of thespectral qualities of their light.

Flashlights of the above description may be used either for producingrelatively short single flashes of predetermined duration, or forilluminating an object for a relatively long period of time, in whichcase the lights are re-ignited at each consecutive half-wave of the A-Ccircuit into which they are connected, and in such an instance they emita light which appears to be constant.

This invention is applicable for either of the two above referred usesof xenon flashlights, or similar flashlights.

Flashlights may be classed into two categories, i.e. flashlights whichare energized by discharging capacitors through the same, andflashlights which are energized from a supply of A-C current. Xenonflashlights, and other flashlights having a similar character, areenergized from a supply of A-C current, and this invention is,therefore, concerned with flashlights which are energized from a supplyof A-C current.

This latter kind of flashlights requires a high-voltage J impulse toinitially ignite the flashlights. Once ignited, the flashlight will keepon operating at the frequency of the supply of A-C current to which itis connected.

The ignition of flashlights of the aforementioned description iseffected by superimposing a high-voltage pulse upon the A-C operatingvoltage of the flashlight.

To this end the supply voltage for the flashlight may be stepped up bymeans of a high-voltage transformer, and the stepped-up voltagesuperimposed upon the normal operating voltage of the flashlight. Theresulting voltage has, therefore, two components of equal frequency, butof different magnitude. In prior art arrangements of this kind thelosses of igniting energy tend to be considerable, unless thehigh-voltage transformer is arranged close to the flashlight, or flashlamp, to be ignited. Another limitation of prior art arrangements ofthis kind consists in that the connection between the highvoltagetransformer and the flashlight, or flash lamp, to be ignited calls forthe use of a relatively expensive highvoltage cable.

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It is, therefore, one object of this invention to provide improvedhigh-voltage ignition systems for electronic flashlights which are notsubject to the aforementioned limitations and/ or drawbacks.

Another prior art ignition sytem for flashlights comprises a capacitorand an electromagnetically operated switching device for charging anddischarging the capacitor in the rhythm of the frequency of an A-Csupply system. In a modification of this prior art ignition system theelectromagnetically operated switching device controls also aninterrupter arranged in the energizing circuit of theelectromagnetically operated switching device and interrupting theenergizing circuit of the electromagnetic switching device in the rhythmof charging and discharging the aforementioned capacitor.

The aforementioned prior art systems are subject to the limitationand/or drawback that the energy which is available for the purpose ofigniting a flashlight, or flash lamp, is solely determined by thecapacitance of the capacitor. Its capacitance cannot be increased atwill because there is a time limit Within each half cycle available forcharging and discharging the capacitor. This limitation is particularlyserious when it is desired to use ignition pulses having a higherfrequency than the A-C supply normally operating the flashlight, orflash lamp.

It is, therefore, another object of this invention to providehigh-voltage ignition systems of the aforementioned description whereinthe energy available for ignition purposes is not limited by the size ofa capacitor and wherein the ignition voltage is, or may be, a voltagehaving a relatively high frequency, or a frequency in excess of thefrequency of the current supply normally operating the flashlight, orflash lamp.

These and other objects of the invention and advantages thereof will bebetter understood from the following detailed description and theaccompanying drawing showing diagrammatically a preferred embodiment ofthe inventio-n.

FIG. 1 is a circuit diagram of a flashlight embodying the presentinvention and FIG. 2 is a diagram of a transformer used for energizingthe circuitry of FIG. 1.

Referring now to the drawing, reference characters L and L have beenapplied to indicate a pair of xenon lamps which are serially connectedinto an electric circuit. The terminals A and A are connected to asupply of A-C current having a circuit voltage of 450 volt and afrequency of 50 c.p.s. A switch S which may be manually operated, ifdesired, is provided to close the circuit of flashlights, or flashlamps, L L The voltage-responsive relay R is shunted across flash lampsL L The relay R is responsive to the supply voltage of 450 volt, andcloses contact r whenever energized. When flashlights, or flash lamps, LL are ignited, and their high initial resistance broken down, thevoltage previously prevailing across relay R breaks down, and the latterbecomes inoperative, resulting in opening of contact 1'. Contact r isarranged in the primary or low-voltage circuit of an impulse transformerT including the primary low-voltage winding I and the secondaryhigh-voltage Winding II. One end of the latter is conductively connectedto a center tap arranged between flashlamps L and L The primary circuitof transformer T may also include the manually operable closing switchZS. The number of turns of winding II of transformer T,. by far exceedsthe number of turns of winding I. Therefore energizing or dc-energizingof winding I results in generation of a very high voltage in winding II.Transformer T is preferablybut not necessarilyan autotransformer, asshown in the drawing. Winding I is energized by terminals connected to asource of A-C having a circuit voltage of 220 volt and a frequency of 50c.p.s. Reference character U has been applied to designate acurrent-responsive relay operating an interrupter 11 including a pair ofcooperating separable contacts. The energizing winding of relay U andthe contacts of interrupter u are connected in series with the primarylow-voltage winding I of transformer T,. The capacitor C is shuntedacross the primary transformer Winding I and the interrupter u.

The energizing circuit of the primary winding I of transformer T isinterrupted whenever the contacts of interrupter u part from each other.Separation of the contacts of interrupter u is effected by thecurrent-responsive relay U. Separation of the contacts of interrupter itcauses the generation of a high-voltage pulse in winding II of impulsetransformer T As a result, either of the two flashlamps L and L isignited, the particular lamp to be ignited depending upon the directionof the high-voltage pulse. Separation of the contacts of interrupter itresults also in the de-energization of relay U. Capacitor C is beingcharged by the 220 volt current supply during the time interval duringwhich the contacts of interrupter u are separated. Contacts ofinterrupter u are moved again to their far latter moves closingposition, resulting in a discharge of capacitor C through winding I oftransformer T This, in turn, causes re-energization of relay U andreopening of the contacts of interrupter u. The high-voltage pulseresulting from the discharge of capacitor C ignites the secondflashlight which had not previously been ignited. Flashlights, orflashlamps, L L are supplied with highvolta-ge pulses until both areignited. Upon being ignited the voltage across both flashlights, orflashlamps, L L breaks down. This causes de-energization of relay R,opening of its contact 1-, thus rendering the ignition systeminoperative. FIG. 2 shows a transformer having a low voltage windingconnected to a 50 c.p.s. current supply and a tapped high voltagewinding. Reference characters A A, have been applied in FIG. 1 toindicate the terminals of the impulsing circuit. Terminal A of the mainsupply and terminal A of its impulsing circuit supply are identical, asclearly apparent from a comparison of FIGS. 1 and 2. Terminals A and Aof FIG. 1 are connected to the taps of the secondary winding of thetransformer bearing the same reference characters. There is an ACvoltage of 450 volt between terminals A and A and an A-C voltage of 220volt between the terminals A and A Relay U is preferably designed insuch a way that it operates at a higher frequency than the frequency ofthe supply of current to which it is connected, e.g. a higher frequencythan 50 c.p.s. In other words, the armature of the relay performsseveral oscillations during each half cycle of its energizing current.Therefore the frequency at which interrupter u operates is a multiple ofthe frequency of the current energizing relay U.

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madewithout departing from the invention, and it is, therefore, aimed in theappended claims to cover all such changes and modifications as fallwithin the true spirit of the invention.

What is claimed is:

1. A high-voltage ignition system for electronic flashlights comprisingin combination:

(a) a flashlight having a pair of electrodes;

(b) a first pair of terminals for connecting said flashlight to a supplyof current;

(0) means for superimposing a voltage upon the voltage prevailingbetween said first pair of terminals to obtain an aggregate voltagesufficient to ignite said flashlight, said voltage superimposing meansincluding an impulse transformer having a primary lowvoltage winding anda secondary high-voltage winding conductively connected to one of saidpair of electrodes of said flashlight to transmit high-voltage firingimpulses to said one of said pair of electrodes;

(d) a second pair of terminals for connecting said primary low-voltagewinding of said impulse transformer to a supply of current;

(e) a current-responsive relay mechanism and an interrupter having apair of separable contacts periodically operated by said relaymechanism;

(f) conductor means for serially connecting said second pair ofterminals, said relay mechanism, said interrupter and said primarylow-voltage winding of said impulse transformer; and

(g) a capacitor shunted across said primary winding of said impulsetransformer and across said pair of separable contacts of saidinterrupter.

2. A high-voltage ignition system as specified in claim 1 including avoltage responsive relay shunted across said pair of electrodes of saidflashlight operative upon breakdown of the voltage drop across said pairof electrodes of said flashlight resulting from firing of saidflashlight, and a switch for controlling energization of said primarylowvoltage winding of said impulse transformer under the control of saidvoltage responsive relay for de-energizing said low-voltage winding uponbreakdown of said voltage drop across said pair of electrodes.

3. A high-voltage ignition system for electronic flashlights comprisingin combination:

(a) a flashlight having a pair of electrodes;

(b) a first supply of current connected to said pair of electrodes ofsaid flashlight;

(c) means for superimposing a voltage upon the voltage of said firstsupply of current to obtain an aggregate voltage suflicient to ignitesaid flashlight, said voltage superimposing means including an impulsetransformer having a primary low-voltage winding and a secondaryhigh-voltage winding connected to one of said pair of electrodes of saidflashlight to transmit high-voltage firing impulses to said one of saidpair of electrodes;

(d a second supply of current for energizing said impulse transformer,said second supply of current having a predetermined frequency;

(e) a current-responsive relay mechanism and an interrupter having apair of separable contacts both serially connected with said primarylow-voltage winding of said impulse transformer into the circuit of saidsecond supply of current, said relay mechanism operating saidinterrupter at a higher frequency than said predetermined frequency; and

(f) a capacitor shunted across said primary winding of said impulsetransformer and across said pair of separable contacts of saidinterrupter.

4. A high-voltage ignition system for electronic flashlights comprisingin combination:

(a) a pair of flashlights each having a pair of electrodes;

(b) conductor means for serially connecting said pair of flashlightsinto an electric circuit, said conductor means including a center tapbetween said pair of flashlights;

(c) means for superimposing a voltage upon the voltage of said electriccircuit to obtain an aggregate voltage suflicient to ignite each of saidpair of flashlights, said voltage superimposing means including animpulse transformer having a primary low-voltage winding and a secondaryhigh-voltage winding conductively connected to said center tap totransmit high-voltage fin'ng impulses to said pair of flashlights;

( d) a current-responsive relay mechanism and an interrupter having apair of separable contacts periodically operated by said relaymechanism;

(e) conductor means for serially connecting said primary low-voltageWinding of said impulse transformer, said relay mechanism and said pairof contacts of said interrupter into an electric circuit; and

(f) a capacitor shunted across said primary low-v-oltage winding of saidimpulse transformer and across said pair of separable contacts of saidinterrupter.

References Cited UNITED STATES PATENTS 12/1945 Clark 315-241 X 12/1954Lautenberger 315-189 X 11/1964 Mutschler 315-17l X 3/ 1965 Michalski315241

1. A HIGH-VOLTAGE IGNITION SYSTEM FOR ELECTRONIC FLASHLIGHTS COMPRISINGIN COMBINATION: (A) A FLASHLIGHT HAVING A PAIR OF ELECTRODES; (B) AFIRST PAIR OF TERMINALS FOR CONNECTING SAID FLASHLIGHT TO A SUPPLY OFCURRENT; (C) MEANS FOR SUPERIMPOSING A VOLTAGE UPON THE VOLTAGEPREVAILING BETWEEN SAID FIRST PAIR OF TERMINALS TO OBTAIN AN AGGREGATEVOLTAGE SUFFICIENT TO IGNITE SAID FLASHLIGHT, SAID VOLTAGE SUPERIMPOSINGMEANS INCLUDING AN IMPULSE TRANSFORMER HAVING A PRIMARY LOWVOLTAGEWINDING AND A SECONDARY HIGH-VOLTAGE WINDING CONDUCTIVELY CONNECTED TOONE OF SAID PAIR OF ELECTRODES OF SAID FLASHLIGHT TO TRANSMITHIGH-VOLTAGE FIRING IMPULSES TO SAID ONE OF SAID PAIR OF ELECTRODES; (D)A SECOND PAIR OF TERMINALS FOR CONNECTING SAID PRIMARY LOW-VOLTAGEWINDING OF SAID IMPULSE TRANSFORMER TO A SUPPLY OF CURRENT; (E) ACURRENT-RESPONSIVE RELAY MECHANISM AND AN INTERRUPTER HAVING A PAIR OFSEPARABLE CONTACTS PERIODICALLY OPERATED BY SAID RELAY MECHANISM; (F)CONDUCTOR MEANS FOR SERIALLY CONNECTING SAID SECOND PAIR OF TERMINALS,SAID RELAY MECHANISM, SAID INTERRUPTER AND SAID PRIMARY LOW-VOLTAGEWINDING OF SAID IMPULSE TRANSFORMER; AND (G) A CAPACITOR SHUNTED ACROSSSAID PRIMARY WINDING OF SAID IMPULSE TRANSFORMER AND ACROSS SAID PAIR OFSEPARABLE CONTACTS OF SAID INTERRUPTER.